Lnk reinforces membrane localisation of Chico-RFP and InRINTRA-CFP. CFP-tagged InRINTRA is shown in ’ panels, RFP-tagged Chico versions in ” panels. Merged pictures are shown in ”’ panels. Signal intensities measured along the indicated lines in ”’ panels are displayed in ”” panels. Quantifications in Additional file 1: Figure S1C. (A-A””) InRINTRA-CFP (A’) and Chico-RFP (A”) in a wild-type background. (B-B””) InRINTRA-CFP (B’) and Chico-RFP (B”) in lnk4Q3. (C-C””) InRINTRA-CFP (C’) and Chico-PH*-RFP (C”) in wild-type tissue. (D-D””) InRINTRA-CFP (D’) and Chico-PH*-RFP (D”) in lnk−/−. (E-E”’) Model of Lnk function in IIS. In wild-type tissue, Lnk ensures enrichment of InR and Chico at the cortical membrane (E). In the absence of Chico, the p60 subunit of PI3K is able to directly bind to InR (E’). In lnk mutants, despite the reduction of InR at the cellular membrane, Chico is able to bind to residual InR; hence the IIS pathway is partially active (E”). By contrast, when Lnk and Chico are lacking, p60 localisation by the residual InR at the membrane is not sufficient to promote pathway activity (E”’). Number of samples analysed: (A) n=8, (B) n=7, (C) n=7, (D) n = 6. Scale bars represent 50 μm.